A huge number of the world's population wears eyeglasses in some form. The term “eyeglasses” generally refers to a device in which lenses are worn in front of the eyes, including but not limited to: spectacles for vision correction; sunglasses for solar protection and safety glasses for eye protection.
Eyeglasses generally comprise a frame for bearing the optically transparent lenses and positioning them appropriately in front of the eyes of the wearer. The frame of eyeglasses generally comprises at least some of the following components: rims to which the lenses are attached; arms or temples which are placed over the ears of the wearer; and a bridge which connects the two lenses (or their rims) together. Part of the frame, typically but not always the bridge, is adapted to rest on the nose of a wearer.
Eyeglasses have evolved over the years from being a purely functional item to being a fashion accessory. The style of eyeglasses has evolved accordingly, in terms of their shape, size and colour. Nowadays, people often desire to have more than one pair of eyeglasses to suit use in different situations, to complement different outfits or simply for the sake of variety. However, the high price of eyeglasses prevents this being a practicable option for many people.
One way in which the style of eyeglasses can be varied relatively cheaply is with interchangeable parts. For example, U.S. Pat. No. 7,690,786 describes eyeglasses having temple arms and a bridge that can quickly and easily be removed and replaced by like parts of a different colour.
WO 95/13558 describes eyeglasses having interchangeable lenses for varying the type of lens according to the requirements of the situation, for example for long distance or short distance viewing, or for protecting from the glare of the sun. The lenses may also be used with eyeglass frame parts of a different colour or style.
These prior art systems do provide some ability to change the style and colour of eyeglasses, but the degree of customisation that is possible is limited. For example, the ability to change the bridge and temple arms only allows the style of eyeglasses to be changed to the extent allowed by changes in the style of those parts.
Furthermore, prior art eyeglass systems having interchangeable parts have been found to be weaker and more flimsy than is desirable for a product designed for long-term use, especially at the join of interchangeable parts.
Where a range of eyeglass styles are available, manufacturers, distributors and retail outlets need to hold enough stock in each style to be able to keep up with demand. Where some styles are unpopular, all the stock in these styles may not be sold and would therefore be disposed of, which is wasteful. Fashion moves on quickly so even popular styles are prone to obsolescence.
Existing methods of manufacturing eyeglasses, including eyeglasses with interchangeable parts, require complex tooling, which impacts on the cost of production. Where components of eyeglasses are injection moulded, the moulding process is made more complex and more expensive where the use of sliding cores or sliding wedges is required. For example, most eyewear frames require grooves around the inner edges of the eye sockets to enable the lens to fit firmly in the frame. These grooves require complex sliding cores to be used in the moulding process. Tooling having such sliding cores is more expensive and has more moving parts than tools without sliding cores, meaning they are susceptible to more wear and tear.